The present invention relates to a signal reproducing device, a typical example of which is an R-DAT.
In an R-DAT, data are recorded on or reproduced from a magnetic tape wound through an angle of about 90.degree. on a rotary drum using a pair of rotary heads A and B spaced 180.degree. from each other. A PCM audio signal is recorded on a track substantially at the middle of the type corresponding to an angle of 90.degree., and sub-code signals (SUB-1 and SUB-2) are recorded before and after the PCM audio signal. A tracking signal (ATF signal) is recorded between the sub-code signal and the PCM audio signal as shown in FIG. 1. In FIG. 1, f.sub.1 designates a pilot signal; f.sub.2, the synchronizing signal of the track (track A) traced by the rotary head A; f.sub.3, the synchronizing signal of the track (track B) traced by the head B and which is different in azimuth from the head A; and f.sub.4, an erasing signal. A tracking error signal is formed according to the level difference between the pilot signal f.sub.1 reproduced from the right track when the synchronizing signal f.sub.2 or f.sub.3 is detected and the pilot signal f.sub.1 reproduced from the left track a predetermined period of time after the detection of the synchronizing signal. In the reproduction (playback) mode, the heads A and B trace the respective tracks in such a manner that the centers of the heads coincide with those of the respective tracks.
In the case where PCM audio signals are to be recorded on the tracks on which predetermined sub-code signals together with tracking signals (ATF signals) have been recorded, for a PCM recording region, each rotary head records the PCM audio signal, and for the remaining region the mode is switched over to a reproduction (playback) mode. In this case, tracking error signals are formed in accordance with the reproduced ATF signals to control the tracking of the rotary heads A and B. As a result, the rotary heads A and B trace tracks in such a manner that the centers of the heads coincide with those of the tracks which have been previously defined. Therefore, as shown in FIG. 2, a track (PCM region) newly formed will not coincide with the track (ATF region and sub-code region) which has been formed. For instance, in the case where the width W of the rotary heads A and B is 20.4 .mu.m and the track pitch p is 13.6 .mu.m, the tracks are shifted 3.4 .mu.m (=(20.4-13.6)/2), the track phase difference being 45.degree..
In order to overcome the above-described difficulty, a method has been proposed in Japanese Patent Application No. 72484/1986 in which, in an after-recording operation, a predetermined offset signal is added to the tracking error signal to make the tracks linear.
Even if the offset signal is added to the tracking error signal in the after-recording operation, the pilot signal reproduction level, for example, will not be equal to that which is determined theoretically. Furthermore, the same apparatus is not always used for the ordinary recording operation and the after-recording operation. Therefore, it is difficult to make the recording tracks and the reproducing tracks completely coincident with each other. Depending on the conditions of the magnetic tape, sometimes offsetting the tracking error signal increases the noncoincidence of the tracks or the frequency of digital data errors.